The following disclosure relates to optical devices for integrated optical circuits. More particularly, the present disclosure relates the devices and methods for thermally stabilizing integrated optical devices.
Growing bandwidth demand has made necessary the use of optical communications at unprecedented small scales and distances, in scenarios such as rack-to-rack links in data centers, board-to-board interconnects, and ultimately for use within multi-core processors [1]. However, at these reduced scales, optical links are only feasible if they can be realized in a small footprint and energy-efficient manner. For this reason, the silicon photonics platform, with its ability to manifest CMOS-compatible photonic devices, is promising for use in next-generation optical links. In particular, microring-based silicon photonic devices have been shown to push the boundaries on the aforementioned metrics of size and energy efficiency [2].
However, as the high-performance functionality of both passive and active microring-based devices have continued to be demonstrated, concerns have grown over the suitability of these devices for use in thermally volatile environments. The high thermo-optic coefficient of silicon, combined with the resonant nature of the microring-based devices, makes the operation of said devices susceptible to thermal fluctuations of only a few kelvin (K) [3]. Additionally, due to fabrication variation, the initial wavelength position of the microring resonance needs to be adjusted to match the operating wavelength of the optical path. It has been shown that using a control system, based on varying the bias current applied to the modulator in response to changes in power (measured off-chip), a microring modulator could maintain error-free performance under thermal fluctuations that would normally render it inoperable [4].